IEC EN 60725 Consideration of Reference Impedances and Public Supply Network Impedances for Use in Determining the Distortion Characteristics of Electrical Equipment

EUROLAB, together with its state-of-the-art accredited laboratories and expert team, provides precise and fast testing services within the scope of IEC EN 60725 testing. This whitepaper records factors and available information when arriving at reference impedances that were previously included in IEC EN 60555 but are now included in parts of IEC EN 61000-3. In addition, information is given on the impedances of public supply networks associated with service current capacities of ≥100 A per phase.

To comply with IEC standard voltages, these systems are described as 230 V/400 V throughout this report. There are significant differences in the way supplies supplied to individual consumers are connected to three-phase systems.

In some countries, all four wires are led to the location of the consumer, allowing the use of three-phase 400 V for large loads, small appliances and lighting circuits are connected to 230 V between a line and neutral. In other countries, lighting circuits for small appliances and lighting are connected between a line and neutral at 230 V, and three wires are led to the consumer's location, allowing the use of 400 V in two phases for large loads.

In rural areas of most countries it is common practice to connect the windings of distribution transformers to two phases of medium voltage systems and to supply low voltage consumers via a phase and return conductor. A wide voltage range is associated with such a supply system.

The supply system impedance associated with the supply to the buildings of a typical residential consumer is determined by the average value of the maximum power demand of all consumers connected to a typical network and the steady-state voltage drop at maximum load used to design the system.

EUROLAB assists manufacturers with IEC EN 60725 test compliance. Our test experts, with their professional working mission and principles, provide you, our manufacturers and suppliers, the best service and controlled testing process in our laboratories. Thanks to these services, businesses receive more effective, high-performance and quality testing services and provide safe, fast and uninterrupted service to their customers.